95-Am-242m

 95-Am-242MJAEA+      EVAL-JAN10 O.Iwamoto,T.Nakagawa,T.Ohsawa,+  
                      DIST-MAY10                       20100318   
----JENDL-4.0         MATERIAL 9547                               
-----INCIDENT NEUTRON DATA                                        
------ENDF-6 FORMAT                                               
                                                                  
History                                                           
06-03 Fission cross section was evaluated with GMA code.          
06-05 Resonance parameters were revised.                          
07-03 Fission spectra were evaluated (below 6 MeV).               
07-05 Theoretical calculation was made with CCONE code.           
      Resonance parameters were modified.                         
07-08 Theoretical calculation was made with CCONE code.           
07-11 Theoretical calculation was made with CCONE code.           
08-03 Interpolation of (5,18) was changed.                        
      Data were compiled as JENDL/AC-2008/1/.                     
09-03 (MF1,MT452) and (MF1,MT455) were revised.                   
09-08 (MF1,MT458) was evaluated.                                  
10-01 Data of prompt gamma rays due to fission were given.        
10-03 Covariance data were given.                                 
                                                                  
                                                                  
MF= 1 General information                                         
  MT=452 Number of Neutrons per fission                           
    Sum of MT's=455 and 456.                                      
                                                                  
  MT=455 Delayed neutron data                                     
    Determined from nu-d of the following three nuclides and      
    partial fission cross sections calculated with CCONE code/2/. 
                                                                  
      Am-243 = 0.006659 *1)                                       
      Am-242 = 0.0049   measured by Saleh et al./3/               
      Am-241 = 0.003154 *1)                                       
                *1) an average of systematics by Tuttle/4/,       
                    Benedetti et al./5/ and Waldo et al./6/       
                                                                  
    Decay constants calculated by Brady and England./7/ were      
    adopted.                                                      
                                                                  
  MT=456 Number of prompt neutrons per fission                    
    (same as JENDL-3.3)                                           
    Maslov's evaluation/8/ was adopted.                           
  * MADLAND-NIX MODEL CALCULATIONS /9/ FITTED TO THE MEASURED     
    DATA OF HOWE ET AL./10/ ABOVE  EMISSIVE FISSION THRESHOLD     
    SUPERPOSITION OF NEUTRON EMISSION IN (N,XNF) REACTIONS /11/   
    AND PROMPT FISSION NEUTRONS IS EMPLOYED.                      
                                                                  
  MT=458 Components of energy release due to fission              
    Total energy and prompt energy were calculated from mass      
    balance using JENDL-4 fission yields data and mass excess     
    evaluation. Mass excess values were from Audi's 2009          
    evaluation/12/. Delayed energy values were calculated from    
    the energy release for infinite irradiation using JENDL FP    
    Decay Data File 2000 and JENDL-4 yields data. For delayed     
    neutron energy, as the JENDL FP Decay Data File 2000/13/ does 
    not include average neutron energy values, the average values 
    were calculated using the formula shown in the report by      
    T.R. England/14/. The fractions of prompt energy were         
    calculated using the fractions of Sher's evaluation/15/ when  
    they were provided. When the fractions were not given by Sher,
    averaged fractions were used.                                 
                                                                  
                                                                  
MF= 2 Resonance parameters                                        
  MT=151                                                          
  Resolved resonance parameters (below 43eV)                      
    Resonance parameters given in JENDL-3.3 were evaluated by     
    Maslov et al./8/                                              
                                                                  
    For the current version, JENDL-3.3 parameters of 0.178eV      
    resonance were modified so as to reproduce the thermal cross  
    sections:                                                     
       fission = 6401+-134b /16,17,18,19, etc./                   
       capture = 1147+-114b /19/                                  
                                                                  
  Unresolved resonance parameters (43eV - 20keV)                  
    Parameters were determined with ASREP code/20/ so as to       
    reproduce the evaluated cross sections in the energy range    
    from 43 eV to 20keV. They are used only for self-shielding    
    calculations.                                                 
                                                                  
                                                                  
     Thermal cross sections and resonance integrals (at 300K)     
    -------------------------------------------------------       
                    0.0253 eV    reson. integ.(*)                 
                     (barns)       (barns)                        
    -------------------------------------------------------       
    total          7547.8                                         
    elastic           5.24                                        
    fission        6401.2           1550                          
    capture        1141.4            236                          
    -------------------------------------------------------       
         (*) In the energy range from 0.5 eV to 10 MeV.           
                                                                  
                                                                  
MF= 3 Neutron cross sections                                      
  Cross sections above the resolved resonance region except for   
  the total (MT=1), elastic scattering (MT=2) and fission cross   
  sections (MT=18, 19, 20, 21, 38) were calculated with CCONE     
  code/2/.                                                        
                                                                  
  MT=1 Total cross section                                        
    From 43 eV to 10 keV, the total cross section was calculated  
    as a sum of partial cross sections. Above 10 keV, the results 
    of CCONE calculation were adopted. The calculation was made   
    with CC OMP of Soukhovitskii et al./21/ The OMP was adjusted  
    by Am-241(n,tot) cross section/22/.                           
                                                                  
  MT=2 Elastic scattering cross section                           
    From 43 eV to 10 keV, calculated with CCONE code.             
    Above 10 keV, calculated as the total - non-elastic scattering
    cross sections.                                               
                                                                  
  MT=51 (n,n') to 1st level                                       
    Calculated with CCONE code. Below 1 eV, 1/v shape was         
    assumed.                                                      
                                                                  
  MT=18 Fission cross section (Above 43eV)                        
    The following experimental data were analyzed with the GMA    
    code /23/:                                                    
      Aleksandrov+/24/, Fomushkin+/25/, Dabbs+/16/, Browne+/17/,  
      Shigin+/26/, Fursov+/27/, Kai+/18/                          
    Above 14MeV, the cross section was determined by eye-guiding. 
    The results of GMA were used to determine the parameters in   
    the CCONE calculation.                                        
                                                                  
  MT=19, 20, 21, 38 Multi-chance fission cross sections           
    Calculated with CCONE code, and renormalized to the total     
    fission cross section (MT=18).                                
                                                                  
                                                                  
MF= 4 Angular distributions of secondary neutrons                 
  MT=2 Elastic scattering                                         
    Calculated with CCONE code.                                   
                                                                  
  MT=18 Fission                                                   
    Isotropic distributions in the laboratory system were assumed.
                                                                  
                                                                  
MF= 5 Energy distributions of secondary neutrons                  
  MT=18 Fission neutron spectra                                   
    Below 6 MeV, calculated by Ohsawa/28/ with modified Madland-  
    Nix formula considering multi-mode fission processes          
    (standard-1, standard-2, superlong).                          
    Above 7 MeV, calculated with CCONE code.                      
                                                                  
  MT=455 Delayed neutron spectra                                  
    Summation calculation by Brady and England /7/ was adopted.   
                                                                  
                                                                  
MF= 6 Energy-angle distributions                                  
    Calculated with CCONE code.                                   
    Distributions from fission (MT=18) are not included.          
                                                                  
                                                                  
MF=12 Photon production multiplicities                            
  MT=18 Fission                                                   
    Calculated from the total energy released by the prompt       
    gamma-rays due to fission given in MF=1/MT=458 and the        
    average energy of gamma-rays.                                 
                                                                  
                                                                  
MF=14 Photon angular distributions                                
  MT=18 Fission                                                   
    Isotoropic distributions were assumed.                        
                                                                  
                                                                  
MF=15 Continuous photon energy spectra                            
  MT=18 Fission                                                   
    Experimental data measured by Verbinski et al./29/ for        
    Pu-239 thermal fission were adopted.                          
                                                                  
                                                                  
MF=31 Covariances of average number of neutrons per fission       
  MT=452 Number of neutrons per fission                           
    Combination of covariances for MT=455 and MT=456.             
                                                                  
  MT=455                                                          
    Error of 20% was assumed.                                     
                                                                  
  MT=456                                                          
    Experimental data of Howe et al./10/ were fitted with a       
    straight line and covariance data were obtained.              
                                                                  
                                                                  
MF=32 Covariances of resonance parameters                         
    Format of LCOMP=0 was adopted.                                
                                                                  
    Covarinaces of JENDL-3.3 /30/ were adopted.                   
                                                                  
                                                                  
MF=33 Covariances of neutron cross sections                       
  Covariances were given to all the cross sections by using       
  KALMAN code/31/ and the covariances of model parameters         
  used in the theoretical calculations.                           
                                                                  
  For the following cross sections, covariances were determined   
  by different methods.                                           
                                                                  
  MT=1, 2 Total and elastic scattering cross sections             
    In the resonance region (below 1 keV), uncertainty of 10 %    
    was added.                                                    
                                                                  
  MT=18 Fission cross section                                     
    Above the resonance region cross section was evaluated with   
    GMA code/23/. The following uncertainties were addeded to     
    the GMA results.                                              
      43 eV to 1 keV     10 %                                     
      1 keV to 100 keV    5 %                                     
      0.1 MeV to 1 MeV    3 %                                     
                                                                  
  MT=102 Capture cross section                                    
    In the resonance region, the following uncertainties were     
    added.                                                        
      1 to 5 eV           5 %                                     
      5 to 10 eV         10 %                                     
      10 to 43 eV        15 %                                     
                                                                  
    Above 43 keV, covariance matrix was obtained with CCONE and   
    KALMAN codes/31/.                                             
                                                                  
                                                                  
MF=34 Covariances for Angular Distributions                       
  MT=2 Elastic scattering                                         
    Covariances were given only to P1 components.                 
                                                                  
                                                                  
MF=35 Covariances for Energy Distributions                        
  MT=18 Fission spectra                                           
    Below 6 MeV, covarinaces of Pu239 fission spectra given in    
    JENDL-3.3 were adopted after multiplying a factor of 9.       
    Above 6 MeV, estimated with CCONE and KALMAN codes.           
                                                                  
                                                                  
***************************************************************** 
  Calculation with CCONE code                                     
***************************************************************** 
                                                                  
  Models and parameters used in the CCONE/2/ calculation          
  1) Coupled channel optical model                                
     Levels in the rotational band were included. Optical model   
     potential and coupled levels are shown in Table 1.           
                                                                  
  2) Two-component exciton model/32/                              
    * Global parametrization of Koning-Duijvestijn/33/            
      was used.                                                   
    * Gamma emission channel/34/ was added to simulate direct     
      and semi-direct capture reaction.                           
                                                                  
  3) Hauser-Feshbach statistical model                            
    * Moldauer width fluctuation correction/35/ was included.     
    * Neutron, gamma and fission decay channel were included.     
    * Transmission coefficients of neutrons were taken from       
      coupled channel calculation in Table 1.                     
    * The level scheme of the target is shown in Table 2.         
    * Level density formula of constant temperature and Fermi-gas 
      model were used with shell energy correction and collective 
      enhancement factor. Parameters are shown in Table 3.        
    * Fission channel:                                            
      Double humped fission barriers were assumed.                
      Fission barrier penetrabilities were calculated with        
      Hill-Wheler formula/36/. Fission barrier parameters were    
      shown in Table 4. Transition state model was used and       
      continuum levels are assumed above the saddles. The level   
      density parameters for inner and outer saddles are shown in 
      Tables 5 and 6, respectively.                               
    * Gamma-ray strength function of Kopecky et al/37/,/38/       
      was used. The prameters are shown in Table 7.               
                                                                  
                                                                  
------------------------------------------------------------------
                              Tables                              
------------------------------------------------------------------
                                                                  
Table 1. Coupled channel calculation                              
  --------------------------------------------------              
  * rigid rotor model was applied                                 
  * coupled levels = 2,6,10 (see Table 2)                         
  * optical potential parameters /21/                             
    Volume:                                                       
      V_0       = 48       MeV                                    
      lambda_HF = 0.004    1/MeV                                  
      C_viso    = 15.9     MeV                                    
      A_v       = 12.04    MeV                                    
      B_v       = 81.36    MeV                                    
      E_a       = 385      MeV                                    
      r_v       = 1.255    fm                                     
      a_v       = 0.58     fm                                     
    Surface:                                                      
      W_0       = 17.2     MeV                                    
      B_s       = 11.19    MeV                                    
      C_s       = 0.01361  1/MeV                                  
      C_wiso    = 23.5     MeV                                    
      r_s       = 1.15     fm                                     
      a_s       = 0.601    fm                                     
    Spin-orbit:                                                   
      V_so      = 5.75     MeV                                    
      lambda_so = 0.005    1/MeV                                  
      W_so      = -3.1     MeV                                    
      B_so      = 160      MeV                                    
      r_so      = 1.1214   fm                                     
      a_so      = 0.59     fm                                     
    Coulomb:                                                      
      C_coul    = 1.3                                             
      r_c       = 1.2452   fm                                     
      a_c       = 0.545    fm                                     
    Deformation:                                                  
      beta_2    = 0.243                                           
      beta_4    = 0.08                                            
      beta_6    = 0.0015                                          
                                                                  
  * Calculated strength function                                  
    S0= 1.26e-4 S1= 2.08e-4 R'=  9.60 fm (En=1 keV)               
  --------------------------------------------------              
                                                                  
Table 2. Level Scheme of Am-242                                   
  -------------------                                             
  No.  Ex(MeV)   J PI                                             
  -------------------                                             
   0  0.00000   1  -                                              
   1  0.04409   0  -                                              
   2  0.04860   5  -  *                                           
   3  0.05270   3  -                                              
   4  0.07582   2  -                                              
   5  0.09900   2  +                                              
   6  0.11400   6  -  *                                           
   7  0.14800   5  -                                              
   8  0.14969   4  -                                              
   9  0.17100   4  -                                              
  10  0.19000   7  -  *                                           
  11  0.19770   3  -                                              
  12  0.23053   1  +                                              
  13  0.24436   3  -                                              
  14  0.26300   6  -                                              
  15  0.26990   3  +                                              
  16  0.27433   1  -                                              
  17  0.28350   7  +                                              
  18  0.28901   4  -                                              
  19  0.29284   2  -                                              
  20  0.29641   2  -                                              
  21  0.30700   5  +                                              
  22  0.32784   3  -                                              
  23  0.33071   3  -                                              
  24  0.34158   0  +                                              
  25  0.34200   5  -                                              
  26  0.35569   2  +                                              
  27  0.36470   2  +                                              
  28  0.37040   4  +                                              
  29  0.37247   4  -                                              
  -------------------                                             
  *) Coupled levels in CC calculation                             
                                                                  
Table 3. Level density parameters                                 
  --------------------------------------------------------        
  Nuclide      a*    Pair  Eshell       T      E0  Ematch         
            1/MeV     MeV     MeV     MeV     MeV     MeV         
  --------------------------------------------------------        
   Am-243 17.8584  0.7698  2.0985  0.4029 -0.9548  3.1071         
   Am-242 18.6337  0.0000  1.6845  0.2795 -0.6541  0.9592         
   Am-241 18.1961  0.7730  1.7328  0.3819 -0.7226  2.8365         
   Am-240 18.5012  0.0000  1.3474  0.2883 -0.6831  1.0000         
   Am-239 18.4349  0.7762  1.5592  0.3648 -0.5528  2.6354         
  --------------------------------------------------------        
                                                                  
Table 4. Fission barrier parameters                               
  ----------------------------------------                        
  Nuclide     V_A    hw_A     V_B    hw_B                         
              MeV     MeV     MeV     MeV                         
  ----------------------------------------                        
   Am-243   6.200   0.800   5.150   0.520                         
   Am-242   6.410   0.600   5.800   0.550                         
   Am-241   6.100   0.800   5.500   0.520                         
   Am-240   6.100   0.650   6.000   0.450                         
   Am-239   6.000   0.800   5.400   0.520                         
  ----------------------------------------                        
                                                                  
Table 5. Level density above inner saddle                         
  --------------------------------------------------------        
  Nuclide      a*    Pair  Eshell       T      E0  Ematch         
            1/MeV     MeV     MeV     MeV     MeV     MeV         
  --------------------------------------------------------        
   Am-243 21.5049  0.8981  2.6000  0.2555 -0.6419  2.0981         
   Am-242 20.8697  0.0000  2.6000  0.3254 -2.4113  2.0000         
   Am-241 21.3526  0.9018  2.6000  0.3213 -1.4929  2.9018         
   Am-240 21.2764  0.0000  2.6000  0.3219 -2.3947  2.0000         
   Am-239 21.2001  0.9056  2.6000  0.3225 -1.4891  2.9056         
  --------------------------------------------------------        
                                                                  
Table 6. Level density above outer saddle                         
  --------------------------------------------------------        
  Nuclide      a*    Pair  Eshell       T      E0  Ematch         
            1/MeV     MeV     MeV     MeV     MeV     MeV         
  --------------------------------------------------------        
   Am-243 21.5049  0.8981  0.6000  0.3532 -0.8019  2.8981         
   Am-242 21.4288  0.0000  0.5600  0.3688 -1.8681  2.2000         
   Am-241 21.3526  0.9018  0.5200  0.3556 -0.7969  2.9018         
   Am-240 21.2764  0.0000  0.4800  0.3567 -1.6981  2.0000         
   Am-239 21.2001  0.9056  0.4400  0.3579 -0.7919  2.9056         
  --------------------------------------------------------        
                                                                  
Table 7. Gamma-ray strength function for Am-243                   
  --------------------------------------------------------        
  * E1: ER = 11.52 (MeV) EG = 2.77 (MeV) SIG = 244.72 (mb)        
        ER = 14.31 (MeV) EG = 4.19 (MeV) SIG = 489.44 (mb)        
  * M1: ER =  6.57 (MeV) EG = 4.00 (MeV) SIG =   1.28 (mb)        
  * E2: ER = 10.10 (MeV) EG = 3.19 (MeV) SIG =   6.92 (mb)        
  --------------------------------------------------------        
                                                                  
                                                                  
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